(a) Field of the Invention
The object of the invention described below is a tackle device of an open-shed jacquard machine, by means of which the warp thread(s) connected thereto can be raised to height (h'), starting from a lift (h) on the knife grate. The height (h')is greater than (h). This feature is called movement reinforcement. This invention relates more particularly, on the one hand, to such a movement-reinforcing tackle device, comprising a movable and a fixed tackle, for which only one fixed grate is needed and, on the other, to such a fixed tackle with mounting devices.
(b) Prior Art
It is known that in a jacquard machine at least one mounting of two complementary rows of hooks can be provided, in which each hook--depending on the row to which it belongs--can be taken along by one of two knives moving up and down in counterphase or can be held in its top or its bottom position by means of selection mechanisms while the knife carries out the up and down movement.
Two hooks (1), (2) standing directly opposite each other, as shown in appended FIGS. 1a and 1b, and belonging to a different complementary row, are connected in this type of jacquard machine to the same tackle cord (3) which bears a movable tackle element (4). The tackle element (4) is composed of two rotary rollers (4') and (4"). The tackle cord (3) is connected to the bottom end of the hooks (1), (2) and hangs down, where it runs over the top roller (4') of tackle element (4). A second tackle cord (5) runs over the bottom roller (4") of tackle element (4), one end of which cord is connected lower down to a grate (6), while the other end is firmly fixed lower down to the top roller (7') of a second movable tackle element (7) with rollers (7') and (7") which is identical to tackle element (4). A third tackle cord (8) runs over the bottom roller (7") of tackle element (7), which cord is connected with one end lower down to a grate (9), and is connected by the other end by means of a harness cord to a warp thread.
The provision of such a tackle device means that, for each warp thread which has to be guided through the jacquard machine, each warp thread can be raised separately as desired to a certain height, depending on the weave to be woven. These two positions of the warp threads correspond to different possible positions for the hooks (1), (2) connected to them.
For example, each hook (1), (2) can be selected at the same height, with known selection means, i.e. in the highest position to which each hook is taken by a knife. If, for example, hook (1) is held up by selection, the knife below (1) will drop, and the knife below hook (2) will then carry out a lift (h). The lowest position of a certain warp thread corresponds to the situation in which both hooks (1), (2) move freely up and down with their respective knives. The highest position of a certain warp thread is achieved when both hooks (1), (2) are in their highest position (see FIG. 1b). For a lift of a hook (2) over a height (h) (compare FIG. 1a and FIG. 1b) one obtains a lift over a height 2h of the warp thread. While the hook (1) was selected up, the lifting of hook (2) over a height (h) causes a lifting of tackle element (4) over a height (h/2). The tackle cord (5) pulls the tackle element (7) up over a height (h), so that tackle cord (8) lifts the warp thread up over a height (2h).
However, such tackle devices have a number of major disadvantages. In the first place, such a mounting requires a fairly large overall height. For, quite a large distance is needed between the underside of the hooks (1), (2) and the warp threads, since the two movable tackle elements (4), (7) have to be suspended below one another and with sufficiently long tackle cords (3), (5), (8) below said hooks (1), (2) and above said warp threads, without hampering the movements of hooks (1), (2) and warp threads. This great overall height makes it necessary for this device to take up a fairly great height between the jacquard machine and the harness, so that the jacquard machine has to be set up higher, in order still to obtain an acceptable bend angle in the harness.
An advantage of the tackle device according to the invention is that a device which now needs only one fixed grate is obtained, with he result that a simpler and cheaper mounting can be achieved.
Another advantage of the invention lies in the fact that the use of only one fixed grate means that a much smaller overall length is needed for the complete tackle device, with the result that the jacquard machine working with it can be placed less high, which again results in a construction which is simpler and cheaper to produce.
A further advantage of the invention lies in the fact that the mounting of the fixed tackle elements slid onto a rail (25) next to each other means a great simplification of the device.
Yet another advantage of the invention, and more specifically of the embodiment of a fixed tackle element shown in FIGS. 3a and 3b, and its possibilities of use lies in the ease with which this type of tackle element can be removed from a whole series of such fixed tackle elements.
Another disadvantage of the known tackle device described above lies in the fact that two grates (6), (9) lying one above the other have to be provided (one for each movable tackle element (4), (7), with the result that a cumbersome and expensive construction is necessary.